The field of the present invention involves external observations of internally generated emissions of electromagnetic radiation, for instance observation of singlet oxygen generation in body organs by infrared fluorescence spectroscopy, and the use of such observations for related diagnosis and therapy. Emissions from a body organ, indicative of its status or of processes occurring in it, and which are transmitted through overlying tissues, are detected such as for control of oxygen therapy.
It is known from analytical chemistry laboratory work that when a reaction in a solution produces or releases singlet oxygen, the solution can effectively glow in, for instance, the infrared region of the electromagnetic spectrum. It has also been known that infrared wavelengths are somewhat transparent through tissue and bones. The prior art has suggested observing deviations from thermal black-body radiation for medical diagnosis (U.S. Pat. No. 2,804,069). Other prior art has involved black-body radiation from localized external areas of an animal's body (U.S. Pat. No. 3,948,249), or absorption or reflection in human tissue of externally-supplied radiation (see for example U.S. Pat. Nos. 2,358,992, 2,640,389, 4,041,932, 4,350,166, 4,414,980). Chemiluminescence has also been detected in human breath, and from internal tissues, for detection of lung cancer, etc., as in U.S. Pat. Nos. 4,534,360 and 4,646,750 to Williams.
Previously, it has not been possible to determine the presence of singlet oxygen in the human body, as it is a rather transient molecule. It is known, however, that singlet oxygen and other species involving unreduced oxygen are toxic. (See for example "Hydroperoxide Metabolism in Mammalian Organs", Chance et al, Physiological Reviews, July 1979, pp 527-605.)